Infestation signs

Sekula-Ortiz says growers or consultants should check field edges and on the bottom stalks for signs of infestation. “You may notice honeydew or sooty mold on your stalks starting at the lower leaves; this is an indication of high sugarcane aphid populations. You will also notice a slight glistening on the leaves; this is honeydew, deposited by sugarcane aphids feeding, that then falls onto the lower leaf. Inspect underneath the leaf above. Sugarcane aphids populate in much greater numbers than the yellow sugarcane aphid and are a lighter yellow in color.”

The yellow sugarcane aphid affects the lower leaves of plants, Villanueva said. Because it is present only during a plant’s early stages, its populations are kept in check by seed treatment and do not pose a problem.

Sekula-Ortiz said aerial and ground applications are providing adequate control. “In two different locations when the spray was conducted by ground using drops on a boom it provided great control. Air and ground sprays should use the highest rates of water to provide good coverage.”

Currently, no treatment threshold exists for sugarcane aphids since it is a new pest in sorghum in Texas and the nation. “We are recommending that you do not let infestation levels exceed 30 percent to 50 percent since they are hard to control,” Sekula-Ortiz said.

She recommends using drops on spray booms and hollow cone nozzles to apply the chemical under the bottom leaves where aphids feed. “A surfactant helps ensure thorough coverage. A high rate of water, 15 to 20 gallons per acre, is recommended for good coverage. The main thing is to keep infestations of the sugarcane aphid from infesting the sorghum head.”

“The aphids consume the plants’ chlorophyll and interfere with the plants’ photosynthesis,” Villanueva said. “So it’s very important that growers spray a recently approved insecticide before the aphids move up into the head, or panicle.”

Once aphids migrate to the head of the sorghum plant, yields are reduced because grains don’t mature; they fail to grow to normal size or numbers, Villanueva said.